Subprojectile launched from telescopic tubes

ABSTRACT

A projectile-subprojectile combination is provided with several concentric, telescopically-slidable, tubular extension members disposed within the projectile body and mechanically connectable to the main projectile body, the subprojectile and each other to form an extended barrel for launching the subprojectile from the projectile body at a predetermined time after the projectile is launched, to increase the final velocity of the subprojectile. In the example shown, the subprojectile is provided with a generally tubular sabot fitted therearound and connectable to the adjacent tubular member.

United States Patent Brothers et a1.

[ Oct. 22, 1974 SUBPROJECTILE LAUNCHED FRO TELESCOPIC TUBES [75] Inventors: Jack Brothers, Panama City, Fla.;

Jerry Pentel, Flanders, NJ.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

[22] Filed: June 7, 1973 [2]] Appl. No.: 367,911

[52] US. Cl 102/69, 102/93, 244/3.1 [51] Int. Cl. F42b 13/50 [58], Field of Search. 102/52, 93, 94, 62, 92.1-92.6, 102/67, 49.3, 56, 69; 244/3.1

[56] v A References Cited UNITED STATES PATENTS 1,292,374 1/1919 Richardson 102/67 3,086,467 4/1963 Gallagher et al. 244/3.1 3,256,816

J 6/1966 Pilcher ...102/49.3

3,417,697 12/1968 Lucy ct a1 102/92 3,677,179 7/1972 Potteiger et a1. 3,714,900 2/1973 Feldman 102/93 Primary Examiner-Samuel W. Engle Attorney, Agent, or FirmEdward J. Kelly; Herbert Berl; Thomas R. Webb 5 7] ABSTRACT 7 Claims, 11 Drawing Figures PAIENIED 001221974 saw an? a mm kn mm SUBPROJECTILE LAUNCHED FROM TELESCOPIC TUBES BACKGROUND AND BRIEF SUMMARY OF THE INVENTION An object of the present invention is to increase the muzzle velocity of a ballistic projectile or missile.

An obvious way to increase the muzzle velocity of a given projectile fired from a given gun barrel is to increase the pressure generated by the propellant, which required that the strength of the barrel be also increased. However, increasing the chamber pressure increases gun barrel wear and thereby reduces gun life, and also adds to the possibility of danger to thegun crew. Moreover, increasing the barrel strength increases the weight and cost of the gun and reduces the mobility thereof.

Another known way to increase the muzzle velocity of a projectile of given caliber or diameter involves (a) mounting a small projectile within a hollow projectile of larger caliber, with a separate propellant disposed between the smaller and larger projectiles, (b) launching the projectile assembly in normal fashion from a gun barrel of the larger caliber, at a given muzzle velocity, and (c) launching the smaller projectile from the larger projectile by means of the separate propellant. In this combination, the smaller projectile is usually termed a sub-caliber projectile, or subprojectile.

In accordance with the present invention, which is an improvement over the projectile-subprojectile combination described above, the subprojectile velocity is further increased by increasing the effective length of the carrier projectile as a barrel for launching the subprojectile, thereby increasing the time and distance that the subprojectile is subjected to the gas pressure generated by the separate propellant. This result is produced by mechanically coupling the subprojectile to the carrier projectile by one or more telescoping tubular extension members concentrically disposed between the two projectiles. When the subprojectile is launched, each element moves forward relative to the next outer element until stopped by overlapping shoulders provided on the adjacent ends of the elements, thus axially extending the elements like a telescope. Preferably, the tubular extension members have a length approximately the same as the tubular barrel portion of the larger projectile, in which case the effective length of the barrel for launching the subprojectile is approximately N times the length of the tubular members, where N is the number of tubular members including the larger projectiles.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial section view of a projectile assembly embodying the present invention.

FIG. 2 is a transverse section view taken on the line 22 of FIG. 1.

FIG. 3 is a transverse section view taken on the line 33 of FIG. 1.

FIGS. 4 and 5 are perspective views of a sabotsubprojectile combination.

FIG. 6 is a fragmentary axial section view showing a modification of FIG. 1.

FIG. 7 is a side view of the retaining ring of FIG. 6.

FIGS. 8, 9, and 11 are perspective views showing successive stages of extension and separation of the projectile assembly of FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGS. 1, 2 and 3, the numeral 1 designates a full caliber projectile comprising an elongated tubular metal body member 3, the forward end of which is closed by a frangible nose cone 5, e.g. of plastic or aluminum, and the rear end of which is closed by a cup-shaped metal base 7. Body member 3 has an internal flange 8 near its forward end forming a rearwardly-facing shoulder or stop 9. The body member may be of steel or aluminum. The base 7 is preferably steel. The projectile 1 is adapted to be tired or launched toward a target in a gun barrel or other tubular launch tube (not shown) by means of a main propellant, which may be in the form of one or more separate propellant bags or a cartridge case. Preferably, the base 7 is provided with an obturator-rotating band 10 of deformable metal for engaging spiral rifling grooves and lands in the gun barrel to minimize leakage of propellant gases past the projectile and to spin the projectile during launch for stabilization thereof during flight.

The base 7 includes a forwardly-opening recess or cavity 11 which contains a supplemental propellant l3, and a fuze 15 for igniting the propellant 13. The recess 11 is partially closed by a support plate 17, of metal or plastic, having a central aperture 19. Coaxially disposed within the tubular body member 3 and nose cone 5, and adjacent to the aperture 19, is an elongated subprojectile means which includes a subprojectile 21 which may comprise a cylindrical metal body portion 23, a nose cone portion 25, and a flared rear portion 27. The subprojectile means 20 preferably also includes a tubular sabot 29, e.g., of aluminum, internally shaped to snugly engage the three portions 23, 25 and 27, of the subprojectile 21, which is shown in elevation in FIG. 1. The exterior of the sabot 29 includes end portions 31 and 33 of the same diameter. The rear portion 33 includes an annular flange 35 of slightly larger diameter forming a forwardly-facing shoulder or stop 36. A metal pusher plate 37, perferably of steel, may be interposed between the aperture 19 and the rear ends of the subprojectile 21 and sabot 29.

The sabot 29 and subprojectile 21 are much smaller in diameter than the projectile body member 3, and are supported within the member 3 1 by means of one or more tubular extension members 39, four of which are shown in the drawing. The tubular members 39 and the tubular projectile body member 3 are substantially coextensive with and concentrically disposed around the sabot 29, and each tubular member 39 is telescopically slidable forwardly within the next outer member, to form a barrel of extended length for launching the sabot and subprojectile at some time after the projectile 1 has been launched. Each tubular member 39 is a relatively thin tube having at least one external projection 41 at the rear end thereof forming a forwardlyfacing shoulder or stop 43, similar to the stop 36 on the sabot 29. Preferably, these projections 41 are formed on each tubular member 39 by an annular flange interrupted by several, e.g., four, axial slots 45 which form gas vents for equalizing the gas pressure on opposite sides of the tubular members 39 during the extension thereof. Each tubular member 39 also has an internal annular flange 47 at its forward end forming a rearwardly-facing shoulder or stop 49, similar to the stop 9 on body member 3. The tubular members 39 are preferably of steel, but could be of fiber or plastic.

The sabot 29 may be longitudinally split, as shown at 51 in FIG. 4, from a point near the flange 35, to form a plurality, e.g. four, of longitudinal fingers 53 joined together before launch at the flange 35 and adapted to be separated and discarded during launch (see FIGS. 5, 10 and 11).

FIGS. 6 and 7 show a modified structure wherein the internal and external flanges 8, 35, 41 and 47 on the members 3, 29 and 39 of FIGS. 1-3 are replaced by expandable split spring rings 55 (one of which is shown in FIGS. 6 and 7 with the subprojectile 21 and sabot 29' extended) mounted within relatively deep annular external grooves 57 at the rear end of each member, and expandable into relatively shallow annular internal grooves 59 at the forward end of each member (3', 29' and 39') when the members are extended. The depth of grooves 57 should be at least equal to the radial thickness of the rings 55. In this embodiment, the forward edges of the rings 55 and the forward side walls of the grooves 59 form the shoulders of FIGS. 1-3.

The manner of firing the composite projectile will now be explained with reference also to FIGS. 8 to 11. First, the projectile 1, as shown in FIG. 1, is launched to a given muzzle velocity. After a predetermined delay, the fuze 15 ignites the propellant 13 to generate gas pressure which forces the subprojectile 21 and its sabot 29 forwardly within the innermost tubular extension member 39, breaking the nose cone 5, as shown in FIG. 8. When the shoulder '36 on the sabot engages the shoulder 49 on the innermost tubular member 39 the latter is started forwardly. Under the continuing gas pressure generated by the propellant 13, the subprojectile 21 is continuously accelerated, while each tubular member 39 is similarly pulled forwardly by the subprojectile, assisted by the gas pressure on the rear end of each tubular member 39, thus containing the gas until all of the tubular members are fully extended as shown in FIG. 9. At this point the subprojectile 21, with its sabot 29, emerges from the extended barrel, by the innermost flange 47 shearing off the flange on the aluminum sabot and continues its flight toward the target at a velocity substantially greater than the muzzle velocity of the projectile 1. If the lengths of the tubular members 39 are substantially equal to the effective internal (barrel) length of the tubular projectile body member 3, and N is the total number of tubular members (including member 3), the effective length of the subprojectile barrel is multiplied by the number N. However, it will be understood that the increase in subprojectile velocity will not be proportional to the number of tubular extension members used, because the gas volume decreases as the barrel length increases. Instead, the first tubular member used will produce the greatest velocity increase, and additional tubular members will produce successively smaller velocity increases.

During the stripping off of the flange 35, the four fingers 53 of the sabot 29 are spread apart and severed by v the fuze 15 may be produced by any known delay means, such as a timing mechanism or fuze cord.

The foregoing disclosure and drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense. We wish it to be understood that we do not desire to be limited to exact details of construction shown and described for obvious modification will occur to a person skilled in the art.

What is claimed is:

1. A projectile, adapted to be launched from a barrel or other full caliber launch tube at a given velocity, comprising:

a. at least two concentric tubular members of substantially the same axial length, each of said tubular members having a" rearwardly-facing iii teFnal shoulder at the forward end thereof. each of said tubular members except the outermost one having a forwardly-facing external shoulder at the rear end thereof, said outermost tubular member being adapted to slidably engage the bore of said full caliber launch tube;

b. a base member closing the rear end of said outermost tubular member;

c. an elongated generally cylindrical subprojectile concentrically disposed within said tubular members and adjacent to said base member, said subprojectile having an axial length at least equal to that of the next adjacent tubular member and having a forwardly-facing external shoulder on the rear end thereof; and

d. means including an explosive propelling charge in said projectile for extending said tubular members and launching said subprojectile from said projectile after said projectile has been launched from said launch tube, to increase the velocity of said subprojectile to a value substantially higher than said given projectile velocity; I

each of said subprojectile and said tubular members being substantially in contact with and telescopically slidable forwardly within the next outer tubular member when said subprojectile is launched until said forwardly-facing shoulders engage said rearwardly-facing shoulders, whereby said tubular members form an extended closed barrel for said subprojectile.

2. A projectile as in claim 1, wherein said launching means comprises:

a. a forwardly-opening cavity in said base member containing said propelling charge;

b. a centrally-apertured support plate partially closing said cavity; and

c. a delay type fuze for igniting said charge.

3. A projectile as in claim 1, wherein the forward end of said outermost tubular member is closed during the launching of said projectile by a frangible nose cone member which is removed by said subprojectile during launching thereof.

4. A projectile as in claim 1, wherein said subprojectile comprises:

a. an elongated cylindrical body having a nose cone section at the forward end andan outwardlyand rearwardly-flared section at the rear end;

b. a sabot fitted around said body and said end sections and slidably engaging the next adjacent tubular member; and

7. A projectile as in claim 1, wherein said internal shoulders on said tubular members are formed by the forward walls of relatively shallow internal annular grooves in said tubular members, and said external shoulders on said tubular members and said subprojectile are formed by the forward edges of split spring rings disposed in relatively deep external annular grooves in said tubular members and said subprojectile, each ring being resiliently expandable into the internal groove of the next outer tubular member. 

1. A projectile, adapted to be launched from a barrel or other full caliber launch tube at a given velocity, comprising: a. at least two concentric tubular members of substantially the same axial length, each of said tubulAr members having a rearwardlyfacing internal shoulder at the forward end thereof, each of said tubular members except the outermost one having a forwardly-facing external shoulder at the rear end thereof, said outermost tubular member being adapted to slidably engage the bore of said full caliber launch tube; b. a base member closing the rear end of said outermost tubular member; c. an elongated generally cylindrical subprojectile concentrically disposed within said tubular members and adjacent to said base member, said subprojectile having an axial length at least equal to that of the next adjacent tubular member and having a forwardly-facing external shoulder on the rear end thereof; and d. means including an explosive propelling charge in said projectile for extending said tubular members and launching said subprojectile from said projectile after said projectile has been launched from said launch tube, to increase the velocity of said subprojectile to a value substantially higher than said given projectile velocity; each of said subprojectile and said tubular members being substantially in contact with and telescopically slidable forwardly within the next outer tubular member when said subprojectile is launched until said forwardly-facing shoulders engage said rearwardly-facing shoulders, whereby said tubular members form an extended closed barrel for said subprojectile.
 2. A projectile as in claim 1, wherein said launching means comprises: a. a forwardly-opening cavity in said base member containing said propelling charge; b. a centrally-apertured support plate partially closing said cavity; and c. a delay type fuze for igniting said charge.
 3. A projectile as in claim 1, wherein the forward end of said outermost tubular member is closed during the launching of said projectile by a frangible nose cone member which is removed by said subprojectile during launching thereof.
 4. A projectile as in claim 1, wherein said subprojectile comprises: a. an elongated cylindrical body having a nose cone section at the forward end and an outwardly- and rearwardly-flared section at the rear end; b. a sabot fitted around said body and said end sections and slidably engaging the next adjacent tubular member; and c. a pusher plate interposed between said apertured plate and the rear ends of said flared section and said sabot.
 5. A projectile as in claim 4, wherein said sabot is formed with longitudinal slits forming elongated fingers extending from a point near the rear end to the forward end thereof, whereby said fingers separate from said body when said subprojectile is launched from said tubular members.
 6. A projectile as in claim 1, wherein said shoulders on said tubular members and said subprojectile are formed by annular flanges on the respective elements.
 7. A projectile as in claim 1, wherein said internal shoulders on said tubular members are formed by the forward walls of relatively shallow internal annular grooves in said tubular members, and said external shoulders on said tubular members and said subprojectile are formed by the forward edges of split spring rings disposed in relatively deep external annular grooves in said tubular members and said subprojectile, each ring being resiliently expandable into the internal groove of the next outer tubular member. 